SPC AC 280544
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1244 AM CDT WED APR 28 2004
   
   VALID 281200Z - 291200Z
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 45 SE OSC 10 SE GRR
   40 SE MKE 10 SSE MSN 20 W LSE 25 ENE FRM 35 SSW SPW 40 WNW OMA 30
   NNE CNK 50 ENE HLC 35 N HLC 45 WSW EAR 35 ESE LIC 30 ENE CNY 50 ESE
   U24 30 NNW MLF 65 S BYI 35 WSW BOI 25 NNE BKE 40 E S80 25 NNE LVM 50
   SE BIL 45 E 4BQ 35 N FAR 30 ESE RRT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 WSW FHU 30 N TUS
   70 ESE SOW LBB 40 NNE CDS 35 ENE CSM 20 WNW TUL 30 NW FYV 10 E FYV
   30 N TXK 35 N LFK 30 SSW BPT ...CONT... 30 SSE CRP 45 ENE LRD 60 WNW
   MFE.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 NW FMY 25 SSE VRB.
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   AN UPPER AIR PATTERN CHANGE WILL TAKE PLACE WEDNESDAY. DEEP UPPER
   TROUGH OVER THE ERN SEABOARD WILL QUICKLY EXIT...REPLACED BY
   BUILDING HEIGHTS OVER THE CNTRL/ERN PORTIONS OF THE COUNTRY. 
   MEANWHILE...VIGOROUS SHORTWAVE TROUGH DIGGING INTO THE NW WILL
   EVOLVE INTO A CLOSED UPPER LOW...GRADUALLY SETTLING SWD INTO THE
   GREAT BASIN BY EARLY THURSDAY. AHEAD OF THIS SYSTEM...A LOW
   AMPLITUDE IMPULSE WILL EJECT NEWD ACROSS THE SRN PLAINS WEDNESDAY
   AND WEDNESDAY NIGHT.
   
   AT THE SURFACE...BAROCLINIC ZONE ASSOCIATED WITH THE GREAT BASIN
   SYSTEM WILL SURGE SWD INTO SRN CA AND NRN AZ BY EARLY THURSDAY. 
   NERN EXTENT OF THE FRONT WILL MOVE SLOWER ONLY REACHING THE UPPER MS
   VLY AND CNTRL PLAINS.
   
   ...SWRN TX...
   PROBABILITY FOR CONVECTION WILL INCREASE OVER THE SRN PLAINS
   WEDNESDAY AS UPSTREAM IMPULSE AND ASSOCIATED COLD POCKET ALOFT EJECT
   NEWD.  WARM CONVEYOR MAY CONTRIBUTE TO ELEVATED CONVECTION/CLOUDS
   DURING PEAK HEATING...LIMITING INSTABILITY IN THE LOWER ELEVATIONS. 
   HOWEVER...AS MAIN PORTION OF THE SHORTWAVE TROUGH MOVES OVER THE
   MOUNTAINS OF NERN MEXICO/TX BIG BEND...TSTMS ARE APT TO DEVELOP BY
   MID-AFTERNOON. GIVEN A GRADUALLY MOISTENING SELY FLOW UP THE RIO
   GRANDE BENEATH WSWLY FLOW ALOFT...A FEW OF THESE TSTMS MAY SURVIVE
   AND MOVE OFF THE MOUNTAINS INTO SWRN TX DURING THE EVENING.  STEEP
   MIDLEVEL LAPSE RATES...35-40 KTS OF DEEP LAYER SHEAR AND RELATIVELY
   DRY SUB-CLOUD ENVIRONMENT INDICATE THAT TSTMS COULD PRODUCE ISOLD
   DAMAGING WINDS AND HAIL.
   
   ...UPPER GREAT LAKES TO THE CNTRL PLAINS...
   SSWLY LOW LEVEL FLOW WILL INCREASE WEDNESDAY ACROSS THE PLAINS...BUT
   RETURN FLOW WILL CARRY ONLY PARTIALLY MODIFIED CP AIR MASS NWD.
   BACKING MIDLEVEL FLOW WILL ADVECT A PLUME OF VERY STEEP LAPSE RATES 
   NEWD ABOVE THIS MEAGER MOISTURE RETURN...CAPPING THE PRE-FRONTAL
   WARM SECTOR.
   
   
   ISOLD VERY HIGH BASED CONVECTION WILL ATTEMPT TO INITIATE FROM MN
   SWWD INTO ERN SD AND CNTRL NEB AS THE COLD FRONT INTERCEPTS NWRN
   EDGE OF RETURNING MOISTURE AND WHERE DEEPER MIXING MAY RESULT IN
   WEAKER CINH.  IF TSTMS CAN INDEED DEVELOP...THERE WILL BE A
   POTENTIAL FOR DAMAGING WIND GUSTS GIVEN THE DRY SUB-CLOUD LAYER. 
   HOWEVER...HEIGHT RISES...CINH...LIMITED MOISTURE SEEM TO ARGUE
   AGAINST SUSTAINED CONVECTION.  AS SUCH...WILL ONLY CARRY A LOW
   PROBABILISTIC CONVECTIVE WIND THREAT CONDITIONAL ON TSTM INITIATION.
   
   
   OTHERWISE...BANDS OF ELEVATED CONVECTION WILL PROBABLY FORM
   OVERNIGHT WEDNESDAY INTO THURSDAY NORTH OF THE FRONT. 
   BUT...INSTABILITY WILL BE LIMITED SUGGESTING THE MAIN THREAT WOULD
   BE SMALL HAIL.
   
   ..RACY/BANACOS.. 04/28/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1300Z